Short interval timer



Feb. 6, 1934. '-H. w. LORD v SHORT INTERVAL TIMER Filed Aug. 3. 1932Inventor: Harold W Lord,

His Attorney.

Patented. Feb. 6,. g 1,946,290

"UNITED STATES A PATENT OFFICE 1,946,290 v snom' m'rrzavar. rmma 'Haroldw. Lord, Schenectady, N. Y., assig'nor to General Electric Company, acorporation of New York Application August 3, 1932. Serial No. 627,389 5Claims. (Cl. 181-18) My invention relates to short interval timersdevice 21 connects with the positive end of the and more particularly totimers useful in measurbattery through the switch 23 and the capacitoring the speed of rapidly moving objects. It is 24, the latter beingshunted byaresistor 25. The 1 the object of my invention to provide animanode of device 20 connects with tap 11 through 5 proved timer whichis simple in construction, relithe resistor 26 and capacitor 2'1 theamount e0 able in operation and is unaffected by the inertia charge ofwhich capacitor is a measure of the of moVing'partsQ time interval to bemeasured. Capacitor 27 is My invention will be better understood fromthe un ed by Sw 28 y which it y be 0001- following description taken inconnection with pl t ly dis ha d before t ti m asurem n 0 theaccompanying drawing, and its scope will b is made. Inprder to measurethe charge received pointed out in the appended claim by capacitor 27 Ihave shown the electron dis- In accordance with my invention I measurecharge devi e29, which may be of t i h vacextremely short periods oftime by supplying a m ype and Whose cath der d. c rcuit 00ncapacitor forsuch a periodwith charging curnects with th e minals of capac 7 and inrent from a known-potential source and subsewhose cathode-anode circuitis the milliammeter 7 quently measure the charge received by the ca- 30in series with the resistance .31. pacitor. v a The operation of theabove described apparatus In the single figure of the drawing which is ais as follows: As long asthe two light beams from circuit diagramillustrating one embodiment of th U 3'ehd 4 fall uninterruptedly upmyinventionIhave shown a form of timer which t p o devices 1 and 2respectively the 75 is adapted for the measurement of the speed ofpedances of the anode circuits of devices 15 and a rapidly movingobject. For this purpose I 16 are a minimum. Hence the control grids of.ploy the photo-electric devices 1 and 2 associated d v ces 0 a d 2 e enegative d these d with which are'the light sources 3 and 4 respecv c tho (1 not P eurrent- Prior to 5 tively, each provided witha suitableoptical sysmaking a Speed measurement, Switch 28 is closed so temrepresented at 5 by which a narrow beam of and op n d in or r t ompl tly discharge light is focused on the corresponding photo-eleccapacitor27. As an object 6 in its movement trio device. The two beams of lightare arranged intercepts the light beam from source 3 the preferably atright angles to the path of moveresistance of device 1 increases causingthe anode ment of the object whose speed is'to be measured impedance ofthe device 15 to increase-to such and ataknown fixed distance apart, thearrange- .an extent that the control grid of device 20 merit being suchthat the object represented for becomes sufliciently positive to causethis device example at 6 successively intercepts the light to begin topass current. Since capacitor 27 is beams. The devices 1 and 2 as wellas the rein the anode circuit ofdevice 20, charging current 5 mainingapparatus in the present embodiment fOr the capac tor will ow from thatp Of the no are shown supplied. by direct current from the batterybetween taps 10 and 11 and will continue battery .7 which is representedas having taps until stopped by the interception of the light beam 8, 9,lOj'and 11 by which the battery is divided from source 4. Are-establishment oi. the beam into sections. The anodes of the twodevices 1 from source 3 in the meantime will not stop the and 2 connectwith the tap 8 while the cathodes flow of charging current to thecapacitor 27 for, ()5 connect with the negative .end of the batterysince device 20 is a ,vapor device, its grid loses through theresistances 12 and 13 respectively. control after the device begins toconduct cur- The two electron discharge amplifying devices rent.Interception of the latter beam'operates 15 and 16, which may be tubesof the high vacuum in a mannersimilar to that already described for 5type, have their cathodes connected bycommon the light beam from source3 causing the device 100 conductor with the tap 9 and have their control16 to have the resistance of its anode circuit ingrids connected withthe cathodes respectively of creased thereby causing the device 21 tobegin the photo devices 1 and 2. The anodes of devices passing current,it being understood that switch 15 and 16 connect respectively throughresist- 23 in the anode circuit of this device is closed. 5 ances 1'7and 18 with the tap 11. Vapor electric By the operation of device 21condenser 24 is 5 or are discharge devices 20 and 21 have their chargedand the cathodes of both devices 20 and cathodes connected with the tap10 of the bat- 21 are raised substantially to the potential oi.

tery through the common resistance 22. The the positive end of thebattery at the moment grids of these devices connect respectively with21 starts conducting. Device 20 accordingly the -anodes of devices 15and 16. The anode of ceases to pass current and therefore the charging11 of condenser 2'! is terminated. By opening switchnthefiowotplatecurrentindeviceiilmaybe stopped. Capacitor 2! is nowcharged an amount mrrespondingwiththelengthottimebetween theinterception of the two light beams. This capacitor and its connectionsare well insulated so that leakage is kept very low. The amount ofcharge given to the capacitor 2'! controls the current fiow through theanode circuit oi device 'aflandthisfiowinthepresentcaseismeasured by themilliammeter 30. Even though this instrument may be sluggish in itsaction the leakage or capacitor 2'! is so small that there is ample timeto read the charge as indicated by the miliiammeter. This instrument maybe calibrated in units of time or may be calibrated to read directly interms of speed o1v the object 6, as for example in feet per second.Under certain circumstances the capacitor 24 and the. resistance 25 maybe eliminated but in that case Lhave found that the current requiredafter device 21 begins passing current. is somewhat higher than it thesemembers are employed in the circuit.

While I have shown means for initiating and terminating the charge ofcapacitor 2'! dependent I upon the passage of an object 6 through thetwo light beams, it will be understood that various other means may beemployed for tripping the devices 20 and 21 whereby the time intervalbetween the tripping of these two devices governs the amount oi chargestored in capacitor 2'7.

I have chosen the particular embodiment described above as illustrativeof my invention and it will be apparent that various other modificationsmay be made without departing from the spirit and scope of my inventionwhich modifications I aim to cover by the appended claims.

Whatlclaimasnewand desire tosecure by letters Patent 0! the UnitedStates. is:

l. A short interval timer comprising a first and a second photo-electricdevice, means for directing a separate light beam into each device,

capacitor, a source oi charging current therea vapor electric dischargedevice responsive interception of the light beam of the first forinitiating the charging oi the capacisaid source, a vapor electricdischarge responsive to an interception of the light of the seconddevice for terminating the of the capacitor and means forindicattotalchargereceivedbytheca'pacitor.

Ashortintervaltimercomprisingafirst a second photo-electric device,means for acapacitornsouroeorchargingourrenttherevapor device positivewith respect to the anodelor,afirstvaporelectricdischls'gedevioeconnected in series withsaid-capacitor and source and controlled by said first photo-electricdevice, a second vapor electric discharge device controlled by saidsecond photo-electric device iorcausingthefirstvapordevicetoceasepassing current and means forindicating the total I charge received by the capacitor.

3.A short interval timerafirst and a second photo-electric device, meansfor directing a separate light beam into each device. a capacitor, asource of charging current therefor, a first vapor electric dischargedevice connected in series with said source and said capaci-- tor forinitiating the charging of the capacitor in response to an interceptionof the beam to the first photo-electric device, means controlled by aninterception of the beam to the second photo-- electric device forrendering the cathode of, said thereof and means for the'charge receivedby the capacitor.

,4. A short interval timer comprising a first and a secondphoto-electric device, means for directing a separate light beam intoeach device. a capacitor, a source of chargingcin'rent therefor, a firstvapor electric discharge device con.nectedinserieswithsaidsourceandsaidcapacitor for initiating thecharging of the capacitor in response to aninterception of the beamtothe first photo-electric device,-a source of potential positive withrespect to the anode of said vapor device, means controlled by aninterception of the beam to said second photo-electric device forconnecting said source of potential with the 11 cathode of said vapordevice and means for measuring the charge received by the capacitor.

5. A short interval timer a first and a second photo-electric device,means for directing a separate light beam into each device. 1 acapacitor, a source of charging current therefor, a first vapor electricdischarge device connected in series with said source and said capacitorfor initiating the charging of the capacitor in response to aninterception of the beam to the 12 first photo-electric device, a sourceof potential positive with respect to the anode of said vapor device, asecond vapor electric device controlled by an interception of the beamto. the second photo-electric device and arranged to connect 135 saidsource of potential with the cathode of said first vapor device andmeans for indicating the charge received by the capacitor.

nsaom w. LORD. n

